three ireland - 'three like home' - italy?

[ca-uk]

I now have a 3 (Ireland) PAYG sim card - i'm getting a bit confused about three like home - i think i'm on the 'best of both' tarriff

When i go here:

three.ie - 3Like Home. Travel 3, pay like home.

And go to the 'best of both' tab then Italy is not mentioned - it says:

Participating Networks on Best of Both:

UK
Australia
Austria
Denmark
Sweden

But in the pay monthly tab the italy flag is there.

If i then go to three.ie - Welcome to our International section. and select best of both and that i'm travelling to italy it says 'Travel 3, pay like home.' - in the 'data roaming' tab it says 'Domestic (RoI) rates apply'

I'm predominantly interested in data, so does my three.ie data package work in italy, or will i be charged mucho mucho?

Clear as mud to me